There is an urgent need for quantitative experimental methodology to analyze diesel soot-coal particulate mixtures. Mixtures of coal dust with diesel soot from machinery are often formed during mining, creating an extremely hazardous environment. Since both coal and diesel soot contain free radicals, EPR can be used in analysis of such mixtures. We have explored the EPR methodology using as examples a diesel soot (sample I), an IBC-101 (Illinois #6) coal (sample II), and their mixtures. At X-band (9.5 GHz) both samples have single-line EPR spectra with only slightly different g-values: (gI-gII)w10-3. Therefore, the EPR signal from a coal-soot mixture cannot reveal the difference between two radical types present. In contrast, at W-band frequencies (94.5 GHz) the g-value resolution is increased by a factor of 10, and this allows us to separate the EPR signals from different mixture components. The results provide a basis for development of a sensitive, quick, and reliable method for analysis of coal/soot mixtures based on high frequency EPR spectroscopy. This has potential applications to occupational and environmental health and safety.